The Blue Water Bridge soars more than 200 feet above the St. Clair River at the southern tip of Lake Huron. Every day, thousands of people cross this span, which stretches for more than a mile between the United States and Canada.

Crossing a bridge like this can be a little unsettling, even for an experienced driver. But what if you could make the trip with your foot off the gas and your hands off the wheel?

It’s possible. And on a recent fall day, the U.S. Army – which has joined companies like Google and Uber to test self-driving vehicles -- came to the Michigan side of the bridge to prove it.

In Port Huron, four tractor-trailers idle near the riverbank.

All of them are testing some type of driverless technology. But the real action is in truck number four, where Paul Rogers will be. He’s the director of the Tank Automotive Research, Development and Engineering Center based near Detroit.

“The last vehicle; the fourth vehicle...we’ll have people in it,” Rogers says. “I’m going to be in it with a driver, who’s not allowed to touch anything. We will be following the other three vehicles, completely autonomously.”

Autonomously. In other words, the truck will drive itself.

The research center is working with the state of Michigan and Auburn University to demonstrate what it calls “truck platooning.” Riding in a convoy, the three lead vehicles will relay speed, steering and braking data to the last truck.

A lot of factors are driving the Army program. Fuel efficiency is one. There’s also no human behind the wheel to get tired and cause an accident.

Most important, on the battlefield, a supply convoy is a prime target for attack. With the new technology, fewer soldiers will be needed in those trucks.

“It’s about saving lives, first and foremost,” Rogers says. “It’s about being more efficient and being able to do more with the number of soldiers and the number of trucks that we have. And it’s always about giving the soldiers what they need to succeed and come home.”

As the trucks pull out, heading for the bridge on-ramp, Bernard Theisen explains the hardware. He’s a program manager with the research center.

LIDAR stands for Light Detection and Ranging, a laser-based sensor used to measure distance. It’s the same principle bats use with sonar. But not even the Batmobile had this little device.

After about an hour spent in bridge traffic and passing through customs, the convoy returns.

Rogers emerges from the rear truck, pleased but low-key.

“No surprises, which is what we expected and what we needed out of this. So, it was very good,” he says.

Kirk Steudle, director of the Michigan Department of Transportation, is obviously impressed.

“We got to the customs plaza on the U.S. side and it’s in automated mode the whole time; the steering wheel is doing these quick little adjustments,” Steudle says. “But as the truck would veer across, you’d see the back tires cross a paint line. And then, you’d realize that your tires went exactly in the same spot. So, where that front truck went is where we went. It was amazing.”

Army officials believe autonomous vehicles can transform how the military operates. The research center is on schedule to roll out 150 more of the vehicles over the next two years.